Computer Systems for Monitoring of Thermal Processes of Foundry Production

The computer system for monitoring of thermal processes which take place at foundry plants is described. Thermal processes are considered in detail as the main processes that occur in the process of casting. Two ways of metal quality control by the method of lost pattern casting thermal analysis are depicted.

Current trends in welding flux development

Welding flux makes significant contribution to weld-metal quality, productivity of welding process and rapid deployment of new materials. Deployment of new materials has been hampered because of lengthy trial-and-test experiments and paucity of methodology for modelling and optimisation in the traditional welding flux development. This paper discussed the contributions made to mitigate the drawbacks of traditional welding flux development in areas of experimentations, prediction modelling and optimisation. Limitations of current efforts were identified and suggested for future research, namely (i) current response models are limited to well-behaved flux systems and do not account for edge and additive effects of flux ingredients (ii) non-incorporation of stakeholder’s preferences concerning the relative importance of quality attributes (iii) lack of prediction and optimisation tools for determining optimal coating factor and flux heights for Shielded Metal Arc Welding and Submerge Arc Welding respectively and (iv) non-continuous response functions and concave regions of the trade-off surface are not considered.

MODELING OF THE GRINDING PROCESS BY MICRO-CUTTING SINGLE ABRASIVE GRAINS. PART 3. FORMATION OF RIS-GROOVES

When grinding on the processed surface of the workpieces of machine parts, a set of RIS-grooves is formed from the action of the vertices of the cutting abrasive grains of the circle. These risks mainly determine the roughness parameters of the treated surface and its physical and mechanical properties. The article presents the results of research of the micro-cutting process of different steels with different abrasive grains in a wide range of cutting speeds. It is shown that increasing the cutting speed during grinding has a positive effect on improving the metal quality of the surface layer of parts.

MathConnex mathematical package for calculating the equivalent thermal conductivity of a strip coil

When heating complex metal loads (layered, fibrous, granular), the gas gaps in them increase the temperature difference across the charge section and lead to an increase in the duration of its heating. Optimizing the time of complex loads heating, which helps to reduce fuel consumption and improve the heated metal quality, requires knowledge of temperature fields in them, which, in turn, depend on the equivalent thermal conductivity of the complex load. For their calculations mathematical modeling can be used, which requires a highly qualified researcher. Carrying out of laboratory and experimental researches takes a lot of time and demands big material expenses, thus the received results are applicable only to a concrete charge. A number of authors give formulas for calculating the equivalent thermal conductivity of the strip coil. However, the practical use of such formulas is difficult due to the presence of difficult to determine parameters: the degree of the strip layers contact, thermal conductivity of different layers of strip and gas gaps between them, heat transfer coefficients by radiation in the gaps between layers. In this case, different formulas for calculating the equivalent thermal conductivity give signifi cantly different results. In the present work, for 20 steel strip coils with height, inner and outer diameters, respectively, 1; 0.4–0.966 m; with a strip thickness of 0.001; 0.003; 0.006 m, the number of layers per side 17; 25 and 50, for the coefficients of strip coil filling 0.70; 0.75; 0.80; 0.85; 0.90; 0.95; 0.97; 0.99, 0.999, the degrees of the strip layers contact 2.8–3.0% and different heated media (air, nitrogen, hydrogen), the reduced thermal conductivity coefficients were calculated according to various formulas using the MathConnex mathematical package (part of MathCadPro). On the basis of the conducted researches the formula for calculation of equivalent thermal conductivity of strip coils is chosen. The results of the calculation are in good agreement with the literature data, it can be used to calculate temperature fields and thermophysical parameters in layered metal loads, as well as to calculate their heating time and furnace performance.

Ultrasonic monitoring of metal burn

The problem of the metal quality estimation after heat treatment by which burn of the steel large work pieces is possible duе to the uneven heating of them in the furnaces is considered. The analysis of possibility to detect the burn zones during the ultrasonic testing by computer simulation of the passage of sound wave through the metal with many small defects is performed. Numerical solution of the wave equation showed that the strong scattering and the absorption of sound wave energy is observed when small volume of defects which is detected using receivers in the echo-method of ultrasonic testing. These receivers are installed on the work pieces surfaces perpendicular to the direction of the sound wave which allow to determine the location of the burned metal zone.

ANALYSIS OF CORROSION RATE OF ASTM A 387 GRADE 12 AND A 283 GRADE FOR SULFURIC ACID TANK MATERIAL

Corrosion is a process of degradation metal quality which is very detrimental in the industry. Especially in an industries related to utilization of acidic liquids such assulfuric acid, hydrochloric acid, etc. If corrosion rate of carbon steel can be estimated, the prediction of remaining life of carbon steel, and the preventive methods of corrosionwould be more appropriate. This will reduce technical, economic and aesthetic losses. The aims of this study was to determine corrosion rate of carbon steel in sulfuric acid. This study used ASTM A 387 Grade 12 and ASTM A 283 Grade A carbon steel type fortank material, where one material is represented by 5 specimen. The corrosion rate of Specimens were measured by the weight loss method for 31 days. The 5 specimens were divided into 3 regions where specimens no.1 and 2 were immersed in sulfuric acid , specimens no.3 were in the middle area or zone level (partially immersed), and specimens no.4 and 5 were not immersed in sulfuric acid. The highst corrosion rate occured on specimen No.3 with maximum corrosion rate was 0,097 mm/y for ASTM A 387 Gr 12 and 0,096 mm/y untuk material ASTM A 283 Gr A. The results of corrosion rate on ASTM A 387 Grade 12 material are lower than corrosion rate of ASTM A 283 Grade A material. This is caused by presence of Mo and Cr alloy elements in ASTM A 387 Grade 12.

Potensi korosivitas pada tanah endapan dataran banjir sungai Citarum di Karawang, Jawa Barat

Corrosion is the biggest problem for equipment that utilised metal, including infrastructure. Corrosion is degradation of metal quality due to the chemical reaction of a metal with the surrounding environment, including soil. Important indicators that contribute to the classification of the rate of corrosivity in soils are water content, pH, types of minerals, soil resistivity values and other chemical-physical parameters. The research area is in Anggadita Village, Klari District, Karawang Regency, West Java Province. Drilling and sampling locations are approximately 300 meters from the Citarum river. The article aimed to investigate between physical and chemical characteristics (soil texture, type of resistivity, pH) of weathered sediments of the Citarum river flood plain to the classification of soil corrosivity. Soil classification in the study area is fine grained and classified into silt with high plasticity (MH-ML) and clay with high plasticity (CH). The results of the analysis of the distribution of potential soil corrosivity in the study area indicate that the level of soil corrosivity is at a high level of corrosive to very high corrosive